CA1203277A - Electric hotplate with a thermostat - Google Patents
Electric hotplate with a thermostatInfo
- Publication number
- CA1203277A CA1203277A CA000431883A CA431883A CA1203277A CA 1203277 A CA1203277 A CA 1203277A CA 000431883 A CA000431883 A CA 000431883A CA 431883 A CA431883 A CA 431883A CA 1203277 A CA1203277 A CA 1203277A
- Authority
- CA
- Canada
- Prior art keywords
- thermostat
- hotplate
- casing
- switch
- electric hotplate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/04—Bases; Housings; Mountings
- H01H37/043—Mountings on controlled apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
- F24C15/00—Details
- F24C15/10—Tops, e.g. hot plates; Rings
- F24C15/102—Tops, e.g. hot plates; Rings electrically heated
- F24C15/105—Constructive details concerning the regulation of the temperature
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
- H05B3/70—Plates of cast metal
Abstract
ABSTRACT
An electric hotplate (2) with a cast iron hotplate body (1) has in its unheated central area (14) a thermostat (19) which, by means of projections (51) on a cover plate (17), is forced into clearly defined contact with the lower surface (50) of the hotplate body (1) in the vicinity of the unheated central area (14). Casing (23) of thermostat (19) has three projections (8), which are supported on surface (50). The unheated central area (14) does not have to be covered by any cover separate from cover plate (17a). Casing (23) has a recess open on one side and which is not closed by a cover.
An electric hotplate (2) with a cast iron hotplate body (1) has in its unheated central area (14) a thermostat (19) which, by means of projections (51) on a cover plate (17), is forced into clearly defined contact with the lower surface (50) of the hotplate body (1) in the vicinity of the unheated central area (14). Casing (23) of thermostat (19) has three projections (8), which are supported on surface (50). The unheated central area (14) does not have to be covered by any cover separate from cover plate (17a). Casing (23) has a recess open on one side and which is not closed by a cover.
Description
ELE~TRIC HOTPLATE WITH A THE~MOSTAT
The invention relates to electric hotplates with a thermostat~
Such a thermostat is knvwn from German Patent 1,123,059. Millions of such thermostats have been incorporated into hotplàtesj they function extremely reliably and are particularly suitable for functioning as thermostats with a high switching hysteresis relatively weakly coupled to the temprature o the heating system. The thermostat comprises a crescent-shaped insulating casing, whose recess contains a snap-act on switch and a bimetallic strip parallel thereto, whilst being fixed by passing through slots of openlngs. The casing is closed by a cover and the thermostat is arranged in the unheated central area o the electric hotplate and partially su~rounds the cast central pin. The cover points downwards and the snap action switch ~nd bim~tallic strip are laterally secured.
~he problem of the present inve;ntion is to provide a thermostat 9' which can be manufactured even less expensively and which has smaller dimensions, whiIst its coupling characteristics to the hotplate are improved. According to the invention, th~is problem is solved in thàt the recess is open to one side in the built-in state.
As a result of the box-like casing, which is open on one side, the bimetallic strip is c~upled better to the temperature to be monitored by it both by convection and by radiation. This is helped if the r~ J~Y
~Ermoslat designed for placing in the unheated central area of the electri~ hotplate has its open side pointing horizontally,;i.e. normally towards the heating system. However, its couplirrg charac-teristics can also be deliberately modified by someother arrangement. It is also posslble to modify the coupling characteristics by the snapraction switch and bimetallic strip being located in a horizontal plane in the built-in state, the co~ing characteristics changing as a function of whether the bimetallic strip faces or is remot;e from the hotplate body.
The very small box-like casing not only has a very uncomplicated cons~ruction and can con-sequently very easily be made from the ceramic material (steatite normally used), but also has a very small weight, so that there is no risk of moisture being deposited on the casing through condensation and which could lead to leakage currents.
Preferably, the end and side walls of the casing surrounding the recess opening project by 1 to 3mm over the snap-action switch and bimetallic strip. As a resùlt of this9 and the other features already described~ it is possible to construct tke thenmostat without a cover.
According to another feature of the invention, the support carrying the snap-action switch and the bimetallic strip can be secured by an auto-matic locking system acting with a limited longitudinal movement.
According to one ernbodimentj in which the ~ . :.; .
~3~'7~
~ 3--therrnostat casing is supported on the c~ver plate and the thermostat is pressed with clearly defined contacts against one surface of the hotplate body in the unheated central area, it is possible to do away with the cover hitherto used for surrounding the thermostat, which contributes to the reduction in manufacturing and assembly costs. The specific heat of the overall arrangement also decreases and there .i5 also no need for the otherwise necessary insulating bushing for the connecting ~eads of the thermostat through the cover. Preferably9 projections are provided on the casing side containing the recess opening and they are pressed into contact with the hotplate body surface. Preferably, three projections are shaped onto the edge surrounding the recess and these in particular have a rounded and optionally a conical configuration. Their unction is on the one;hand to ensure adequate spacing between the functional part of the thermostat arranged in the recess and the hotplate body, and on the other hand to ensure a clearly defined engagement, whilst still permitting a certain ventilation o the thermostat from below.
Advantageously, a perforated, cup shaped covering part can be provided for the unheated central area. As a result of the tight, la~ticed structure o the cup, which ls earthed as a result o the earthing of the hotplate body, despite an effective ventilation o the central area, it: forms such a complete electrical protection that a temperature sensor can be used, whose switch casing is at least open on one side.
Advantageously, the temperature sensor of the thermostat is arranged in the switch casing. The overal.l level of temperature monitoring of the hotplate can be lowered somewhat, so that it is possible to us~ a simpler, robust switch, which is integrated with a temperature sensor. The tempera`ture limiting action is still completely satisfactory~, although at a first glance it would not appear appropriate to lower the temperature level to be monitored, before senslng it with a thermostat.
In addition9 a hotplate'is proposed, in which the thermostat caslng is o'pen on its side remote rom the hotplate' an~ ~he' $witch parts inserted in the recesses are p~tècted against falling out by:
at least one fix~g part, which at least partly covers the slots and can be pIaced in recesses of the switch casing, said fixing part di.rectly engaging with the cover plate, or the hotplate.body. As a result~ ~t is :possible to:do away with'the cap which 'is normally surrounding the thermostat, which natur.ally leads to cost savings. Cost savings also result from the omission of the thermostat:casing cover, particularly when assembling the swi'tch ~rom individual'parts. The fix~ng part has a lower weight than the hitherto known cover, which leads' to cost'savings ~from the material side and to a reduction of the specific heat of the casing. Due to the fact thatthere is now need to use a covering cap, it is also possible to do without an insul'ating bushing fo.r.the l.ead-in wires for the thermostat. Features of.the prefe~red further developments of -the :invention can be ga-thered from the subclaims and description in conjunction with the drawings, whereby the individual features can be realised either alone or in random combinations in connection with any embodiment of -the invention. Non-limitative embodiments of the invention are described in gxeater detail hereinafter relàtive to the drawings, wllerein show-FIG. 1 a diagrammatic partial section through a hotplate with a thermostat.
FIG. 2 a larger-scale, plan view of a thermo-stat, viewed from above in FIG. 1.
FIG. 3 a partly broken away view from below of a hotplate wi~h a covering part.
FIG. 4 a section along line IV-IV of FIG. 3.
FIG. 5 a partial section through a hotplate.
FIG. 6 a detail of a thermostat.
FIGS. 7 to 9 partial perspective views of fi~ing parts.
FIGS. 1~ and 11 partial sections through the thermostat casing and cover plate.
FIG. 12 a longitudinal sectional through a thermostat along line XII in FIG. 13.
FIG. 13 a section along the bent section line XIII in FIG. 12.
FIG. 14 a detailed section along line XIV in FIG. 13.
FIG. 15 a cross-section along line XV in FIG. 13.
FIG. 16 a view from below of a hotplate equipped with a thermostat.
I'he electr:ic hotplate 2 shown in Fig. 1 has a hotplate body 1 made from cast material, preferably lYJ J il~ll ~
cast iron, with a heating ring area 11, which is closed to the outside and inside by d.ownwardly projecting ring ribs 1?, 13. Electric.heating resistors are located in ~e heating rir,lg area a.n~ are emb`edded in insulating.material in slots of the hotplate body.
Within the inner ring ri,b 12 therç is an unheated central zone 14~ in whose c~ntre there is a lug 15 in the form of a downwardly projecting,cas't,pin., i.nto whose tap hole is screwed a clamping bolt 16~
.The bottom of the,electric hotplate is enclosed by a profiled cover plate 17 which~ in the embodiment of Fig 1, rests on the lower edge of the annular outer ring rib 13, which covers the entire bottom surface of the hotplate and is pressed'upwards by bolt 16 and a nut 18 screwed thereon.
A thermostat 19 is arranged in the uhheated central zone 14. It is connected by means of lead-1n wires 20 and s.erves to switch off the heating system or parts thereof, .if the hotplate assumes a temperature above its set thermostat temperature.'It is desirable for the thermostat to respond with a certain time lag, because as ,a result, it can be set in such a way that it permanent'ly switches off an elevated in~ial cooking or boiling power:a~ter it has,responded, in order then to leave an adequate , final cooking or boiling power.
' Thermostat 19 is shown on'a larger scale in Fig 2. Its construction and function corresponcl,s to German Patent,1,123,05g, to which reference is made.
The functional parts 3 of the'thermostat are arranged 3~
in a recess 25 of a casing 23, made from insulating mater~, such as steati~e, and said parts 3 are fixed by insertion in slots of casing 23. This involves a bimetallic strip 4, which is fitte~ to a support 30 inserted in a slot 31 and moves the spring reed of a catch spring of a snap-action switch 5. On one end of the catch spring i.s provided a contact, which cooperates with a fixed opposite contact and a comlecting strip 2~, which like connecting strip 28 are inserted in slots 27 of the casing and consequently secured for supplying power to the catch spring. In plan view, the casing is largely crescent-shaped, or could also be described as rectangular with a recess on one longitudinal side and shoulders on the facing longitudinal side.
As can be gathered from Figs 1 and 2, there are three projections 8 on top 7 on the casing edge 6 surrounding recess 25 and tcwards which recess 25 has its opening. These projections are constructed in one piece with casing 23 and have a conical configurat-ion with a rounded tip.
It can be gathered from Fig 1 that thermostat 19 is arranged in the central area in such a way that the central lug 15 is positioned in the vicini~y of recess 9 on one longitudinal side of the casing, sàid side having a flattened portion, which passes into a 1attened portion 10 o the lower surface 50 of central area 14.
Cover pl.ate 17 preferably only has one projection 51~ which is constructed as an inwardly directed reinforcing corrugation of the cover plate and presses onto the flat bottom 52 of casing 230 As a result9 projections 8 are deined and are firrnly pressed against surface 50 of the hotplate hody in the vicinity of the central area. Although ~he opening of recess 25 is open to the top, but is covered at a certain distancefrom the surface 5Q of the hotplate body and ;s consequently protected against contact.
On tightening bolt 16 or nut 18, the thermostat ls consequently pressed into contact with the hotplate body. The maintenance of this pressure is assisted by the elastic.construction of the.cover plate, but could also be assised by a corresponding spring element and/or the shaping of the end cover or projection 51. For example, it would he conceivable to make the area around the projection resili.ent by providing slsjts in the cover plate.
In Fig 39 the hea~ing ring area ll is covered towards the bottom by a cover plate 17a,~
which rests on rirns 12 and 13 and which is .centered by a bent-round porti.on 72 in the interi.or of inner rim 12.
By means of two connecting s~tri~os 74, thermostat 19 is switched into one of the hotplate circuits. Leads 74 are l.ed out of the central area by means of an insulating bushing 75 facing the thermostat 19. The central area is covered by a covering part 76, which is in the form .of a relativ.ely flat cup with a substantiall.y planar bottom 77, a ~032 77 substantially cylindrical surface 78 and an outwardly projecting support flange 7~ at the end of the cylindrical surface 78. This support flange 79 rests on a shoulder'80 of cover plate 17a and presses the latter against the bottom of rim 12. The cup-shaped covering part 76 is made from perforated steel metal material with a relatively large thîckness of p~eferabl,y over 0.8mm and in the present embodiment it is lmm thick. In the present embodimentl the sheet meta'l material has circular holes 8~,arranged in a random manner and whose diatheter is only a ~ew millimetres. The pe-rforated area is preferably between one and two thirds and in particularly preferred manner represents hal~ of the total surface area. As a result of the manufactureof the cup from sheet metal material perforated prior to cup deformation, the holes are arranged over the entire cup surface, but in the vicinity of the outer,support flange79~form such a relatively continuous surface, that there is a uniform pressing of cover plate 17a,against rim l2.
Covering part 76 is secured by means of a nut 81 screwed onto the clamping bolt 1~, so that the cover plate 17a' is also ~ixed.
Thermostat 23 is open at one side, i.e.
its bimetallic strip and current-carrying switch parts are not covered by a separate insulating cover.
It is virtually impossible in normal operation that anything could come into ~ntact with these current-carrying parts, without simultaneously coming into contact with the earthing s~stem, which is provided ~2~
by the latticed or perforated coverirlg part.
The hotplate in Fig 5 corresponds to that of Fig l, apart from the differences described hereinafter.
In the vicinity o thermostat 19, cover plate 17b is provided with a plurality of vents.
Between the cas;ng 23 o thermostat l9 and cover plate 17s there are two fixing parts 24.
Fig 6 shows a larger-scale deta'il of casing 23 of a thermostat 19b. Its casing 23 has ~hre~ holes 26 which, in the case of conventional thermostats~ serve to fix a cover from above onto the casing. To the rigl;t of ~ig 3, there is a slot 27, through which passes a connecting element 28 o thermostat l9b and which is enclosed by a fixing part 24. On the bottom of fixing part 24~ there is a cylin'rical pin, which is inserted in the dntted-line hole 26, Thus, it covers,the connecting element 28 and prevents any unintentional movem'ent of the comple~e switch mechanism ou.t of the casing and.' supports the thermostat on the'cover plate.or the.
hotplate body. For fixing the left-hand connecting element 29 (Fig 2~ and the switch support 30, in this case a common fixing element is used, which engages with a c~lindr'ical shoulder in hole 26 and with at least one further shoulder in the left-hand slot 27 or i.n recess 31 for switch s~pport 30.
Fig 7 is a view from below of a fixing element 24, which has a circu~ar cylindrical shoulder 32 and a para:llelepipedic sho,ulder 33.,,It is placed on 7 ~
casing 23 of thermostat l9 in such a way that shoulder 32 engages in hole 26 and shoulder 33 in slot 27.
Fig. 8 shows the fixing element 24 according to Fig. 4. On the side of the fixing elemen-t opposite to shoulders 32, 33 is provided a rib 34, which pro-vides a linear engagement of cover plate 17.
Fixing element 35 according to Fig. 9 has on its bot-tom surface 36, an elongated shoulder 37, which is as long as the fixing element is wide, as well as a cylindrical shoulder 32 and a rib 34.
In Fig. 10, casing 23 of thermostat 19 engages flush on the bottom surface 38 of the unheated central area 14 of the hotplate. The connecting element 28 is inserted in a slot 27, which is open at one side. One shoulder 32 of fixing element 24 engages in hole 26, whilst its second shoulder 33 engages in slot 27 above connecting element 28 and is consequently secured against rotation. Cover plate 17b is arranged above fixing element 24 and is screwed onto central lug 15 in the manner stated hereinbefore. It engages on rib 34 of fixing element 24. As a result of this arrange-ment, in the case of a turned-round built-in state, all the switch or thermostat elements are protected against falling out, so that they do not have to be cemented in.
Fig. 11 shows that on its side remote from the hotplate, a further fixing element 40 has, in addition to two ribs 34, a higher shoulder 41, which engages in an opening 42 of cover plate 17. As a , result of shoulder 41, it can easily be established from the outside, i.e. from above in Fig 8, whether fixing element 40 is correctly po~itioned.
To the right and alongside opening 42 for shoulder 41, cov~r plate 17b has two slots 43, which have been formed by stamping out and bending away.
Figs 12 to 15 show a thermostat 11. It has a casing 113 made from ceramic~insulating material, D e.g. steatite, having the shape of an elongated, rectangularl~ defined box, whase one long side is open. Correspondingly, the casing has ~o narrow end walls 115, 117, two side walls 119, 121 and a bottom 122, which bound a recess 123, whilst the only remaining slde is the open side 124.
In recess 123 is placed a rigid sheet metal material support 125j which extends along side wall 121 and is supported thereon with a stamped part 1~1. A short, strong bime~tallic strip 127 is fixed parallel thereto by spot weld 128, by means of which is also fixed a movable abuSment 129 constructed as a flexible s~eet metal strip with a one-sided bend. By turning an adjustment scrçw 143, which is acceptable through an opening 144 in side wall 121, it is possible to adjust the ~nd of the particular abutment with respect to bimetallic strip 127 and consequently the basic setting of a snap-action switch 131. The latter has a catch spring ann 133, reinforced by laterally edged parts and its centre is stamped out in reed-like manner and forms a catch spring l~O, which is supported in the abutment 129 under bending bias. At its free end, the catch spring arm carries a contact 134 whilst the other end is supported in a knife-edge bearing 135, which is located on an upward bend 137 of su~port 125. In order not to load.the knife-edge bearing 135 by the currents to be switched, a connecting stranded wire 145 is welded to the catch spring.arm 133 and to support 125.
To permit the free operation of the bi-metallic strip, support 12.5:has a number of steps and at its one end 139 has two outer, foot-like projections, which are placed in .two cavities 147, whereof one is open towards recess 123 and towards the open side 124, whilst the other is arranged in undercut manner by an interrnediate end wall portion 144 projecting towards the recess~ so that end 139 when located in the bottom-facing cavi~y 147, prevents a movement of the support in the direction of open 2Q side 124. An opening 151 in the bottom area is provided only for manufacturing reasons, in order to permit the manufacture of the undercut cavity 147 in a single split mould without cores and slides..
The other end 153 of the support orrns an electrical connecting lug or a connecting lead 1559 which is welded to sai.d lug.
End 153 forms a narrow extension in the vicinity of bottom 122 ar.~d projects through an opening 157, which passes through:the co.rner between end wall 117 and bottom I22 and consequently forms an ~3~27~
opening accessible from the end wall and the bottotTI, whose height (at right angles to the plane of support 125) is significantly greater than the thickness of the support (approximately 3 to 4 times).
The end of support 125 within recess 12.3 forms a stop face 159 which, in the fitted state, faces a protection surface 161 (cf Fig 14), which forms a step in end wall 117. From the open side 124, the protection surface can extend up ~ opening 157 and namely up to a height roughly corresponding to the centre of opening ~57.
An oppos te contact 163, placed on an opposi~e contact support 164, faces contact 134 of snap-act~n switch 131. Support 164 is inserted in a slot 163, which has the flat V-shaped configuration shown in Fig 13 and consequently relatively reliably fixes in clearance-free manner, the correspondingly dimensioned opposite contact support 164 during its insertion. The final securing action is provided by weldin~ a connecting lead 166 to the portion of the opposite contact support 164 projecting outwards over bottom 122.
During manufacture, the complete functional unit consist;ng of support 125, bimetallic strip 127 and snap-action switch 131 are completely preassembled~
The short, strong bimetallic strip 127, which tapers somewhat to a free end, is welded to the support, together with the abuttnent 129, the catch spring arm 133 and catch spring 130 are hung in and the stranded wire 145 is welded. Opposite contact support 164 is ~ g~
inserted in slot 165 and then the aforementioned preassembled unit is introduced into recess 123.
Initially, end 153 is slopingly place~ through opening 157 in such a way that the stop ~ace 159 S of support 125 (cf Figs 12 or 14) is above the protection surface 161. Thus, support 125 can be moved so far to the left that end 139 can be swung in in the direction of the curved arrow 167 in E'ig 13 and end'139 can still be freely moved from the proj,ect-ing end wall portion 149. When support 125 has beenintroduced into its position engaging on bottom 122, it is only necessary to form support 125 to the right and, as a result of its own bias, catch spring arm 133 presses support 125 downwards in Figs 12 and 14, so that stop face 159 faces protection surface 161 and now no longer permits a leftwa~d displacement of support 125, so that the snap-action switch support is secured in the positlon shown in Figs 12 and 14.
The final securing action is brought about in that on welding connecting lead,155,'the latter is forced into the part of opening 157 remaining above end 153, for which purpose the lead can be slightly bent.
Figs 13 and 15 show that fixing has taken place in such a way thatthe current-carrying or live unit formed by support ,l25, bimetallic strip 127 and snap-action switch 131 is a ¢onsiderable distance from open side 1249 i.e. the;end and side walls 115 to 121 project between 1 and 3rnm above sald parts.
In view o the relatively limited width of the recess (,less than lOmm), this provides an adequate pro~ection ~ y~
against contact, so that there is no need for a cover projecting over recess L~. This improves the thermal couplability of the thermostat and further reduces its already limited overall weightl which is advantageous from the switching and leakage current behaviour standpoint.
The snap-action switch adjusted by raising the movable abutment 129 with respect -to bimetallic strip 127 is operated if, as a result of heating, b metallic strip 127 has bent so far up~ards in Fig 12 that the snapping point of the switch is reached. Contacts 134, 1639 which are shown closed, are then opened.
Fig 16 shows the thermostat 111 in its lS arrangement on a hotplate 170f The latter is a cast plate with a heated ring area 171S wh re thermostat 111 is arranged in the unheated central area 172 surro~nded by a rim 173. It is placed on one side of a cast-on fixing connection 174 with its open side 124 towards rim 173 and consequently pointing towards the heating system. The connecting leads 155, 166 pass directly to corresponding terminal pins, which project from the ceramic embedding material in the heated ring area and lead to one or more heating resistors in the heated ring area.
In the position represented in Fig 16, the interior of the thermostat is freely accessible to the heat coming from the hotplate, both by riation and by conduction and convectionO By changing the position, in such a way that e.gO the open side 124 faces fixing connection 174,, these couplings can be modified. Normally, the thermostat is fitted in such a positi,on that side 121 engages on the hotplate body, so that the bimetal]ic strip is nearer thereto.
The coup]ing characteristics are also changed by turning round (engagement of side 119~.
The thermostat is particularly easily manufactured. Its casing,comprises a single ceramic piece~ which can be produced in a single split mould and onto it a,re only fitted two parts, which can both be fixed by insertion, without any need of cementing or the,like. These parts being the opposite contact support and the preassembled unit formed by the support, bimetallic strip and snap-action switch.
The single adjustment screw is readily accessible.
The individual parts are ~ixed by the welding of the connecting lead~ which'is necessary in any case.
The thermostat can still be used in many different ways and its coupling (fast,or slow acting) can be adapted to different requirements by me~y turning round at the time of fitting. It has been found that ther~ is no need with this thermostat to cover the central area 172 of the hotplate with a separate cover, as has been hitherto, whilst there is no increased risks of leakage currents.
It is also advantageous thatthe two connections 153, 164 are located in the vicinity of a narrow side of the casing9 so that the connecting leads leading therefrom are short and can pass in juxtaposed manner through a recess in the rim 173.
The invention relates to electric hotplates with a thermostat~
Such a thermostat is knvwn from German Patent 1,123,059. Millions of such thermostats have been incorporated into hotplàtesj they function extremely reliably and are particularly suitable for functioning as thermostats with a high switching hysteresis relatively weakly coupled to the temprature o the heating system. The thermostat comprises a crescent-shaped insulating casing, whose recess contains a snap-act on switch and a bimetallic strip parallel thereto, whilst being fixed by passing through slots of openlngs. The casing is closed by a cover and the thermostat is arranged in the unheated central area o the electric hotplate and partially su~rounds the cast central pin. The cover points downwards and the snap action switch ~nd bim~tallic strip are laterally secured.
~he problem of the present inve;ntion is to provide a thermostat 9' which can be manufactured even less expensively and which has smaller dimensions, whiIst its coupling characteristics to the hotplate are improved. According to the invention, th~is problem is solved in thàt the recess is open to one side in the built-in state.
As a result of the box-like casing, which is open on one side, the bimetallic strip is c~upled better to the temperature to be monitored by it both by convection and by radiation. This is helped if the r~ J~Y
~Ermoslat designed for placing in the unheated central area of the electri~ hotplate has its open side pointing horizontally,;i.e. normally towards the heating system. However, its couplirrg charac-teristics can also be deliberately modified by someother arrangement. It is also posslble to modify the coupling characteristics by the snapraction switch and bimetallic strip being located in a horizontal plane in the built-in state, the co~ing characteristics changing as a function of whether the bimetallic strip faces or is remot;e from the hotplate body.
The very small box-like casing not only has a very uncomplicated cons~ruction and can con-sequently very easily be made from the ceramic material (steatite normally used), but also has a very small weight, so that there is no risk of moisture being deposited on the casing through condensation and which could lead to leakage currents.
Preferably, the end and side walls of the casing surrounding the recess opening project by 1 to 3mm over the snap-action switch and bimetallic strip. As a resùlt of this9 and the other features already described~ it is possible to construct tke thenmostat without a cover.
According to another feature of the invention, the support carrying the snap-action switch and the bimetallic strip can be secured by an auto-matic locking system acting with a limited longitudinal movement.
According to one ernbodimentj in which the ~ . :.; .
~3~'7~
~ 3--therrnostat casing is supported on the c~ver plate and the thermostat is pressed with clearly defined contacts against one surface of the hotplate body in the unheated central area, it is possible to do away with the cover hitherto used for surrounding the thermostat, which contributes to the reduction in manufacturing and assembly costs. The specific heat of the overall arrangement also decreases and there .i5 also no need for the otherwise necessary insulating bushing for the connecting ~eads of the thermostat through the cover. Preferably9 projections are provided on the casing side containing the recess opening and they are pressed into contact with the hotplate body surface. Preferably, three projections are shaped onto the edge surrounding the recess and these in particular have a rounded and optionally a conical configuration. Their unction is on the one;hand to ensure adequate spacing between the functional part of the thermostat arranged in the recess and the hotplate body, and on the other hand to ensure a clearly defined engagement, whilst still permitting a certain ventilation o the thermostat from below.
Advantageously, a perforated, cup shaped covering part can be provided for the unheated central area. As a result of the tight, la~ticed structure o the cup, which ls earthed as a result o the earthing of the hotplate body, despite an effective ventilation o the central area, it: forms such a complete electrical protection that a temperature sensor can be used, whose switch casing is at least open on one side.
Advantageously, the temperature sensor of the thermostat is arranged in the switch casing. The overal.l level of temperature monitoring of the hotplate can be lowered somewhat, so that it is possible to us~ a simpler, robust switch, which is integrated with a temperature sensor. The tempera`ture limiting action is still completely satisfactory~, although at a first glance it would not appear appropriate to lower the temperature level to be monitored, before senslng it with a thermostat.
In addition9 a hotplate'is proposed, in which the thermostat caslng is o'pen on its side remote rom the hotplate' an~ ~he' $witch parts inserted in the recesses are p~tècted against falling out by:
at least one fix~g part, which at least partly covers the slots and can be pIaced in recesses of the switch casing, said fixing part di.rectly engaging with the cover plate, or the hotplate.body. As a result~ ~t is :possible to:do away with'the cap which 'is normally surrounding the thermostat, which natur.ally leads to cost savings. Cost savings also result from the omission of the thermostat:casing cover, particularly when assembling the swi'tch ~rom individual'parts. The fix~ng part has a lower weight than the hitherto known cover, which leads' to cost'savings ~from the material side and to a reduction of the specific heat of the casing. Due to the fact thatthere is now need to use a covering cap, it is also possible to do without an insul'ating bushing fo.r.the l.ead-in wires for the thermostat. Features of.the prefe~red further developments of -the :invention can be ga-thered from the subclaims and description in conjunction with the drawings, whereby the individual features can be realised either alone or in random combinations in connection with any embodiment of -the invention. Non-limitative embodiments of the invention are described in gxeater detail hereinafter relàtive to the drawings, wllerein show-FIG. 1 a diagrammatic partial section through a hotplate with a thermostat.
FIG. 2 a larger-scale, plan view of a thermo-stat, viewed from above in FIG. 1.
FIG. 3 a partly broken away view from below of a hotplate wi~h a covering part.
FIG. 4 a section along line IV-IV of FIG. 3.
FIG. 5 a partial section through a hotplate.
FIG. 6 a detail of a thermostat.
FIGS. 7 to 9 partial perspective views of fi~ing parts.
FIGS. 1~ and 11 partial sections through the thermostat casing and cover plate.
FIG. 12 a longitudinal sectional through a thermostat along line XII in FIG. 13.
FIG. 13 a section along the bent section line XIII in FIG. 12.
FIG. 14 a detailed section along line XIV in FIG. 13.
FIG. 15 a cross-section along line XV in FIG. 13.
FIG. 16 a view from below of a hotplate equipped with a thermostat.
I'he electr:ic hotplate 2 shown in Fig. 1 has a hotplate body 1 made from cast material, preferably lYJ J il~ll ~
cast iron, with a heating ring area 11, which is closed to the outside and inside by d.ownwardly projecting ring ribs 1?, 13. Electric.heating resistors are located in ~e heating rir,lg area a.n~ are emb`edded in insulating.material in slots of the hotplate body.
Within the inner ring ri,b 12 therç is an unheated central zone 14~ in whose c~ntre there is a lug 15 in the form of a downwardly projecting,cas't,pin., i.nto whose tap hole is screwed a clamping bolt 16~
.The bottom of the,electric hotplate is enclosed by a profiled cover plate 17 which~ in the embodiment of Fig 1, rests on the lower edge of the annular outer ring rib 13, which covers the entire bottom surface of the hotplate and is pressed'upwards by bolt 16 and a nut 18 screwed thereon.
A thermostat 19 is arranged in the uhheated central zone 14. It is connected by means of lead-1n wires 20 and s.erves to switch off the heating system or parts thereof, .if the hotplate assumes a temperature above its set thermostat temperature.'It is desirable for the thermostat to respond with a certain time lag, because as ,a result, it can be set in such a way that it permanent'ly switches off an elevated in~ial cooking or boiling power:a~ter it has,responded, in order then to leave an adequate , final cooking or boiling power.
' Thermostat 19 is shown on'a larger scale in Fig 2. Its construction and function corresponcl,s to German Patent,1,123,05g, to which reference is made.
The functional parts 3 of the'thermostat are arranged 3~
in a recess 25 of a casing 23, made from insulating mater~, such as steati~e, and said parts 3 are fixed by insertion in slots of casing 23. This involves a bimetallic strip 4, which is fitte~ to a support 30 inserted in a slot 31 and moves the spring reed of a catch spring of a snap-action switch 5. On one end of the catch spring i.s provided a contact, which cooperates with a fixed opposite contact and a comlecting strip 2~, which like connecting strip 28 are inserted in slots 27 of the casing and consequently secured for supplying power to the catch spring. In plan view, the casing is largely crescent-shaped, or could also be described as rectangular with a recess on one longitudinal side and shoulders on the facing longitudinal side.
As can be gathered from Figs 1 and 2, there are three projections 8 on top 7 on the casing edge 6 surrounding recess 25 and tcwards which recess 25 has its opening. These projections are constructed in one piece with casing 23 and have a conical configurat-ion with a rounded tip.
It can be gathered from Fig 1 that thermostat 19 is arranged in the central area in such a way that the central lug 15 is positioned in the vicini~y of recess 9 on one longitudinal side of the casing, sàid side having a flattened portion, which passes into a 1attened portion 10 o the lower surface 50 of central area 14.
Cover pl.ate 17 preferably only has one projection 51~ which is constructed as an inwardly directed reinforcing corrugation of the cover plate and presses onto the flat bottom 52 of casing 230 As a result9 projections 8 are deined and are firrnly pressed against surface 50 of the hotplate hody in the vicinity of the central area. Although ~he opening of recess 25 is open to the top, but is covered at a certain distancefrom the surface 5Q of the hotplate body and ;s consequently protected against contact.
On tightening bolt 16 or nut 18, the thermostat ls consequently pressed into contact with the hotplate body. The maintenance of this pressure is assisted by the elastic.construction of the.cover plate, but could also be assised by a corresponding spring element and/or the shaping of the end cover or projection 51. For example, it would he conceivable to make the area around the projection resili.ent by providing slsjts in the cover plate.
In Fig 39 the hea~ing ring area ll is covered towards the bottom by a cover plate 17a,~
which rests on rirns 12 and 13 and which is .centered by a bent-round porti.on 72 in the interi.or of inner rim 12.
By means of two connecting s~tri~os 74, thermostat 19 is switched into one of the hotplate circuits. Leads 74 are l.ed out of the central area by means of an insulating bushing 75 facing the thermostat 19. The central area is covered by a covering part 76, which is in the form .of a relativ.ely flat cup with a substantiall.y planar bottom 77, a ~032 77 substantially cylindrical surface 78 and an outwardly projecting support flange 7~ at the end of the cylindrical surface 78. This support flange 79 rests on a shoulder'80 of cover plate 17a and presses the latter against the bottom of rim 12. The cup-shaped covering part 76 is made from perforated steel metal material with a relatively large thîckness of p~eferabl,y over 0.8mm and in the present embodiment it is lmm thick. In the present embodimentl the sheet meta'l material has circular holes 8~,arranged in a random manner and whose diatheter is only a ~ew millimetres. The pe-rforated area is preferably between one and two thirds and in particularly preferred manner represents hal~ of the total surface area. As a result of the manufactureof the cup from sheet metal material perforated prior to cup deformation, the holes are arranged over the entire cup surface, but in the vicinity of the outer,support flange79~form such a relatively continuous surface, that there is a uniform pressing of cover plate 17a,against rim l2.
Covering part 76 is secured by means of a nut 81 screwed onto the clamping bolt 1~, so that the cover plate 17a' is also ~ixed.
Thermostat 23 is open at one side, i.e.
its bimetallic strip and current-carrying switch parts are not covered by a separate insulating cover.
It is virtually impossible in normal operation that anything could come into ~ntact with these current-carrying parts, without simultaneously coming into contact with the earthing s~stem, which is provided ~2~
by the latticed or perforated coverirlg part.
The hotplate in Fig 5 corresponds to that of Fig l, apart from the differences described hereinafter.
In the vicinity o thermostat 19, cover plate 17b is provided with a plurality of vents.
Between the cas;ng 23 o thermostat l9 and cover plate 17s there are two fixing parts 24.
Fig 6 shows a larger-scale deta'il of casing 23 of a thermostat 19b. Its casing 23 has ~hre~ holes 26 which, in the case of conventional thermostats~ serve to fix a cover from above onto the casing. To the rigl;t of ~ig 3, there is a slot 27, through which passes a connecting element 28 o thermostat l9b and which is enclosed by a fixing part 24. On the bottom of fixing part 24~ there is a cylin'rical pin, which is inserted in the dntted-line hole 26, Thus, it covers,the connecting element 28 and prevents any unintentional movem'ent of the comple~e switch mechanism ou.t of the casing and.' supports the thermostat on the'cover plate.or the.
hotplate body. For fixing the left-hand connecting element 29 (Fig 2~ and the switch support 30, in this case a common fixing element is used, which engages with a c~lindr'ical shoulder in hole 26 and with at least one further shoulder in the left-hand slot 27 or i.n recess 31 for switch s~pport 30.
Fig 7 is a view from below of a fixing element 24, which has a circu~ar cylindrical shoulder 32 and a para:llelepipedic sho,ulder 33.,,It is placed on 7 ~
casing 23 of thermostat l9 in such a way that shoulder 32 engages in hole 26 and shoulder 33 in slot 27.
Fig. 8 shows the fixing element 24 according to Fig. 4. On the side of the fixing elemen-t opposite to shoulders 32, 33 is provided a rib 34, which pro-vides a linear engagement of cover plate 17.
Fixing element 35 according to Fig. 9 has on its bot-tom surface 36, an elongated shoulder 37, which is as long as the fixing element is wide, as well as a cylindrical shoulder 32 and a rib 34.
In Fig. 10, casing 23 of thermostat 19 engages flush on the bottom surface 38 of the unheated central area 14 of the hotplate. The connecting element 28 is inserted in a slot 27, which is open at one side. One shoulder 32 of fixing element 24 engages in hole 26, whilst its second shoulder 33 engages in slot 27 above connecting element 28 and is consequently secured against rotation. Cover plate 17b is arranged above fixing element 24 and is screwed onto central lug 15 in the manner stated hereinbefore. It engages on rib 34 of fixing element 24. As a result of this arrange-ment, in the case of a turned-round built-in state, all the switch or thermostat elements are protected against falling out, so that they do not have to be cemented in.
Fig. 11 shows that on its side remote from the hotplate, a further fixing element 40 has, in addition to two ribs 34, a higher shoulder 41, which engages in an opening 42 of cover plate 17. As a , result of shoulder 41, it can easily be established from the outside, i.e. from above in Fig 8, whether fixing element 40 is correctly po~itioned.
To the right and alongside opening 42 for shoulder 41, cov~r plate 17b has two slots 43, which have been formed by stamping out and bending away.
Figs 12 to 15 show a thermostat 11. It has a casing 113 made from ceramic~insulating material, D e.g. steatite, having the shape of an elongated, rectangularl~ defined box, whase one long side is open. Correspondingly, the casing has ~o narrow end walls 115, 117, two side walls 119, 121 and a bottom 122, which bound a recess 123, whilst the only remaining slde is the open side 124.
In recess 123 is placed a rigid sheet metal material support 125j which extends along side wall 121 and is supported thereon with a stamped part 1~1. A short, strong bime~tallic strip 127 is fixed parallel thereto by spot weld 128, by means of which is also fixed a movable abuSment 129 constructed as a flexible s~eet metal strip with a one-sided bend. By turning an adjustment scrçw 143, which is acceptable through an opening 144 in side wall 121, it is possible to adjust the ~nd of the particular abutment with respect to bimetallic strip 127 and consequently the basic setting of a snap-action switch 131. The latter has a catch spring ann 133, reinforced by laterally edged parts and its centre is stamped out in reed-like manner and forms a catch spring l~O, which is supported in the abutment 129 under bending bias. At its free end, the catch spring arm carries a contact 134 whilst the other end is supported in a knife-edge bearing 135, which is located on an upward bend 137 of su~port 125. In order not to load.the knife-edge bearing 135 by the currents to be switched, a connecting stranded wire 145 is welded to the catch spring.arm 133 and to support 125.
To permit the free operation of the bi-metallic strip, support 12.5:has a number of steps and at its one end 139 has two outer, foot-like projections, which are placed in .two cavities 147, whereof one is open towards recess 123 and towards the open side 124, whilst the other is arranged in undercut manner by an interrnediate end wall portion 144 projecting towards the recess~ so that end 139 when located in the bottom-facing cavi~y 147, prevents a movement of the support in the direction of open 2Q side 124. An opening 151 in the bottom area is provided only for manufacturing reasons, in order to permit the manufacture of the undercut cavity 147 in a single split mould without cores and slides..
The other end 153 of the support orrns an electrical connecting lug or a connecting lead 1559 which is welded to sai.d lug.
End 153 forms a narrow extension in the vicinity of bottom 122 ar.~d projects through an opening 157, which passes through:the co.rner between end wall 117 and bottom I22 and consequently forms an ~3~27~
opening accessible from the end wall and the bottotTI, whose height (at right angles to the plane of support 125) is significantly greater than the thickness of the support (approximately 3 to 4 times).
The end of support 125 within recess 12.3 forms a stop face 159 which, in the fitted state, faces a protection surface 161 (cf Fig 14), which forms a step in end wall 117. From the open side 124, the protection surface can extend up ~ opening 157 and namely up to a height roughly corresponding to the centre of opening ~57.
An oppos te contact 163, placed on an opposi~e contact support 164, faces contact 134 of snap-act~n switch 131. Support 164 is inserted in a slot 163, which has the flat V-shaped configuration shown in Fig 13 and consequently relatively reliably fixes in clearance-free manner, the correspondingly dimensioned opposite contact support 164 during its insertion. The final securing action is provided by weldin~ a connecting lead 166 to the portion of the opposite contact support 164 projecting outwards over bottom 122.
During manufacture, the complete functional unit consist;ng of support 125, bimetallic strip 127 and snap-action switch 131 are completely preassembled~
The short, strong bimetallic strip 127, which tapers somewhat to a free end, is welded to the support, together with the abuttnent 129, the catch spring arm 133 and catch spring 130 are hung in and the stranded wire 145 is welded. Opposite contact support 164 is ~ g~
inserted in slot 165 and then the aforementioned preassembled unit is introduced into recess 123.
Initially, end 153 is slopingly place~ through opening 157 in such a way that the stop ~ace 159 S of support 125 (cf Figs 12 or 14) is above the protection surface 161. Thus, support 125 can be moved so far to the left that end 139 can be swung in in the direction of the curved arrow 167 in E'ig 13 and end'139 can still be freely moved from the proj,ect-ing end wall portion 149. When support 125 has beenintroduced into its position engaging on bottom 122, it is only necessary to form support 125 to the right and, as a result of its own bias, catch spring arm 133 presses support 125 downwards in Figs 12 and 14, so that stop face 159 faces protection surface 161 and now no longer permits a leftwa~d displacement of support 125, so that the snap-action switch support is secured in the positlon shown in Figs 12 and 14.
The final securing action is brought about in that on welding connecting lead,155,'the latter is forced into the part of opening 157 remaining above end 153, for which purpose the lead can be slightly bent.
Figs 13 and 15 show that fixing has taken place in such a way thatthe current-carrying or live unit formed by support ,l25, bimetallic strip 127 and snap-action switch 131 is a ¢onsiderable distance from open side 1249 i.e. the;end and side walls 115 to 121 project between 1 and 3rnm above sald parts.
In view o the relatively limited width of the recess (,less than lOmm), this provides an adequate pro~ection ~ y~
against contact, so that there is no need for a cover projecting over recess L~. This improves the thermal couplability of the thermostat and further reduces its already limited overall weightl which is advantageous from the switching and leakage current behaviour standpoint.
The snap-action switch adjusted by raising the movable abutment 129 with respect -to bimetallic strip 127 is operated if, as a result of heating, b metallic strip 127 has bent so far up~ards in Fig 12 that the snapping point of the switch is reached. Contacts 134, 1639 which are shown closed, are then opened.
Fig 16 shows the thermostat 111 in its lS arrangement on a hotplate 170f The latter is a cast plate with a heated ring area 171S wh re thermostat 111 is arranged in the unheated central area 172 surro~nded by a rim 173. It is placed on one side of a cast-on fixing connection 174 with its open side 124 towards rim 173 and consequently pointing towards the heating system. The connecting leads 155, 166 pass directly to corresponding terminal pins, which project from the ceramic embedding material in the heated ring area and lead to one or more heating resistors in the heated ring area.
In the position represented in Fig 16, the interior of the thermostat is freely accessible to the heat coming from the hotplate, both by riation and by conduction and convectionO By changing the position, in such a way that e.gO the open side 124 faces fixing connection 174,, these couplings can be modified. Normally, the thermostat is fitted in such a positi,on that side 121 engages on the hotplate body, so that the bimetal]ic strip is nearer thereto.
The coup]ing characteristics are also changed by turning round (engagement of side 119~.
The thermostat is particularly easily manufactured. Its casing,comprises a single ceramic piece~ which can be produced in a single split mould and onto it a,re only fitted two parts, which can both be fixed by insertion, without any need of cementing or the,like. These parts being the opposite contact support and the preassembled unit formed by the support, bimetallic strip and snap-action switch.
The single adjustment screw is readily accessible.
The individual parts are ~ixed by the welding of the connecting lead~ which'is necessary in any case.
The thermostat can still be used in many different ways and its coupling (fast,or slow acting) can be adapted to different requirements by me~y turning round at the time of fitting. It has been found that ther~ is no need with this thermostat to cover the central area 172 of the hotplate with a separate cover, as has been hitherto, whilst there is no increased risks of leakage currents.
It is also advantageous thatthe two connections 153, 164 are located in the vicinity of a narrow side of the casing9 so that the connecting leads leading therefrom are short and can pass in juxtaposed manner through a recess in the rim 173.
Claims (27)
1. In an electric hotplate:
a hotplate body having a top and a bottom side;
a thermostat arranged at the bottom side of the hotplate body;
the thermostat comprising:
a casing made from an insulating material forming a casing body enclosing a casing space, said casing space being open and without a casing cover on one side thereof;
a temperature sensitive snap switch arranged in the casing space of said casing body by inserting a temperature sensitive element with a switch support and a snap switch contact member of a switch unit on one hand and a cooperating counter contact unit on the other hand;
the switch support with the temperature sensitive element and the counter contact unit being fixed by insertion in insertion openings in said casing body;
wherein the insertion openings in said casing body are arranged for inserting the switch unit includ-ing the snap switch contact member and the counter contact unit through the open side of the casing body.
a hotplate body having a top and a bottom side;
a thermostat arranged at the bottom side of the hotplate body;
the thermostat comprising:
a casing made from an insulating material forming a casing body enclosing a casing space, said casing space being open and without a casing cover on one side thereof;
a temperature sensitive snap switch arranged in the casing space of said casing body by inserting a temperature sensitive element with a switch support and a snap switch contact member of a switch unit on one hand and a cooperating counter contact unit on the other hand;
the switch support with the temperature sensitive element and the counter contact unit being fixed by insertion in insertion openings in said casing body;
wherein the insertion openings in said casing body are arranged for inserting the switch unit includ-ing the snap switch contact member and the counter contact unit through the open side of the casing body.
2. An electric hotplate according to claim 1 wherein the switch support, the snap switch contact member and the temperature sensitive element are formed by a preassembled unit secured in its position beside the open lying side of the casing body by insertion of the switch support in the insertion openings.
3. Electric hotplate according to claim 1, characterized in that the casing of the thermostat is supported on a cover plate covering the bottom of the electric hotplate and the thermostat is pressed in clearly defined contact with a surface of hotplate body in a not direct heated central area.
4. Electric hotplate according to claim 3, characterized in that pressing takes place in the vicinity of a flattened portion of the hotplate body.
5. Electric hotplate according to claim 3, characterized in that the cover plate has inwardly directed projections, preferably constructed as stamped-out portions, which act on the thermostat casing, the cover plate and/or projections being constructed resiliently.
6. Electric hotplate according to claim 1, characterized in that the open side of the casing body of the thermostat faces the hotplate body in a distance therefrom.
7. Electric hotplate according to claim 6, characterized in that projections are provided on the open side of the casing body and are pressed into contact with the bottom surface of the hotplate body.
8. Electric hotplate according to claim 7, characterized in that the preferably three projections are shaped onto a casing body edge surrounding the open side and in particular have a rounded and optionally a conical configuration.
9. Electric hotplate according to claim 3, characterized in that the cover plate covering the bottom of the hotplate body leaves the central area free and in the vicinity of the central area is pro-vided a separate, perforated covering part, which is fixed by a central bolt engaging in the central area of the hotplate body and which projects through the central portion of the covering part and is a cup made from perforated sheet metal material.
10. Electric hotplate according to claim 9, characterized in that the cup-shaped covering part is made from a sheet metal material, perforated prior to deformation and which has a relatively great thickness (preferably more than 0.8 mm), the diameter of the holes only being a few mm, whereby the perforated surface preferably represents between one and two thirds, and particularly preferably half of the total surface area.
11. Electric hotplate according to claim 9, characterized in that the perforations are also provided in the substantially cylindrical surface area of the covering part.
12. Electric hotplate according to claim 9, characterized in that substantially over its entire circumference, an edge or rim of the covering part rests on a shoulder of the annular cover plate and presses the latter against a hotplate body rim sur-rounding the central area.
13. Electric hotplate according to claim 12, characterized in that the edge of the covering part has an all-round, outwardly projecting support flange.
14. Electric hotplate according to claim 3, characterized in that the thermostat casing body is open on its side remote from the hotplate body and the snap switch inserted in the insertion opening is protected against falling out by at least one fixing part at least partly covering these openings and insertable in recesses of the thermostat casing body, said fixing part directly engaging on the cover plate covering the bottom of the hotplate body.
15. Electric hotplate according to claim 14, characterized in that the fixing part has at least one cylindrical shoulder for engaging in a hole provided in the thermostat casing body and at least one cylindrical shoulder for engaging in a slot.
16. Electric hotplate according to claim 14, characterized in that the fixing part has on its side facing the cover plate at least one engagement lug, engagement rib, etc.
17. Electric hotplate according to claim 14, characterized in that in the vicinity of the thermostat, the cover plate has openings, holes, slots, etc.
18. Electric hotplate according to claim 14, characterized in that on its side remote from the hotplate body, the fixing part has a shoulder extending through a corresponding opening in the cover plate.
19. Thermostat according to claim 1, characterized in that in the built-in position, the snap switch and a bimetallic strip of the temperature sensitive element are in a horizontal plane.
20. Thermostat according to claim 1, character-ized in that end and side walls of the thermostat casing body surrounding the recess opening project over the snap switch and the temperature sensitive element by preferably 1 to 3 mm.
21. Thermostat according to claim 1, character-ized in that the switch support and the temperature sensitive element are fixed by an automatic locking system acting with limited longitudinal movement of the support with respect to the casing.
22. Thermostat according to claim 21, character-ized in that the automatic locking system comprises at least one insertion opening formed by a cavity in the interior of a casing end wall, in which engages one end of the switch support and is also secured therein against a movement in the direction to the open side of the casing body, that in the vicinity of the other end of the switch support there is a portion project-ing into or through an insertion opening in the other end wall and is secured in this insertion open-ing against movement in the direction to the open side, but can move to a limited extent in a direction at right angles thereto, whilst a stop face is also provided which cooperates with a protection surface provided on the corresponding end wall, the distance between the end engaging in the cavity and the stop face being greater than the distance from an end wall portion adjacent to the cavity to the protection surface, but is smaller than the distance to a portion of the corresponding end wall adjacent to the protec-tion surface.
23. Thermostat according to claim 22, character-ized in that by the snap switch contact member engaging on the opposite counter contact, the switch support is forced in the direction of its position associated with the protection surface.
24. Thermostat according to claims 22 or 23, characterized in that a switch support portion project-ing through the insertion opening forms a connecting lug and a connecting lead can be inserted between the wall of the insertion opening and the portion.
25. Thermostat according to claim 1, character-ized in that the counter contact unit, cooperating with the snap switch contact member, is inserted into a preferably cross-sectionally arcuate or flat V-shaped slot and is secured by the welding of the associated connecting lead.
26. Thermostat according to claim 1, character-ized in that two electrical connections of the snap switch are arranged in the vicinity of a narrow side of the thermostat casing body.
27. Thermostat according to claim 3, character-ized in that the open side of the thermostat casing body placed in the unheated central area of the hotplate body is facing horizontally.
Applications Claiming Priority (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEG8219461.0 | 1982-07-07 | ||
| DE19828219461 DE8219461U1 (en) | 1982-07-07 | 1982-07-07 | ELECTRIC COOKING PLATE |
| DEP3226264.7 | 1982-07-14 | ||
| DE19823226264 DE3226264A1 (en) | 1982-07-14 | 1982-07-14 | Temperature limiter for electrical heating or warming apparatuses, especially electrical cooking plates |
| DEG8227145.3 | 1982-09-28 | ||
| DE8227145U DE8227145U1 (en) | 1982-09-28 | 1982-09-28 | Electric hotplate |
| DE19833301689 DE3301689A1 (en) | 1983-01-20 | 1983-01-20 | Electrical hot plate |
| DEP3301689.5 | 1983-01-20 | ||
| DE8301364U DE8301364U1 (en) | 1982-07-07 | 1983-01-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1203277A true CA1203277A (en) | 1986-04-15 |
Family
ID=27510720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000431883A Expired CA1203277A (en) | 1982-07-07 | 1983-07-06 | Electric hotplate with a thermostat |
Country Status (8)
| Country | Link |
|---|---|
| US (2) | US4605841A (en) |
| EP (1) | EP0100861B1 (en) |
| AU (1) | AU560969B2 (en) |
| CA (1) | CA1203277A (en) |
| DE (1) | DE8301364U1 (en) |
| FI (1) | FI75461C (en) |
| GR (1) | GR82636B (en) |
| PT (1) | PT76992B (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3336311A1 (en) * | 1983-10-06 | 1985-04-18 | E.G.O. Elektro-Geräte Blanc u. Fischer, 7519 Oberderdingen | ELECTRIC COOKING PLATE |
| DE8515560U1 (en) * | 1985-05-25 | 1985-08-29 | E.G.O. Elektro-Geräte Blanc u. Fischer, 7519 Oberderdingen | Hotplate heating |
| DE3606794A1 (en) * | 1986-03-01 | 1987-09-03 | Ego Elektro Blanc & Fischer | ELECTRIC COOKING PLATE |
| DE3617742A1 (en) * | 1986-05-27 | 1987-12-03 | Ego Elektro Blanc & Fischer | ELECTRIC COOKING PLATE |
| US4755655A (en) * | 1986-12-04 | 1988-07-05 | General Electric Company | Thermal protection arrangement for solid disk glass cooktop |
| DE3709438A1 (en) * | 1987-03-22 | 1988-10-06 | Ego Elektro Blanc & Fischer | ELECTRIC COOKING PLATE |
| JP3894577B2 (en) * | 1996-07-15 | 2007-03-22 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Heating element |
| GB2317544B (en) * | 1996-09-18 | 2000-10-11 | Otter Controls Ltd | Improvements relating to electric heating elements and controls therefor |
| GB2317991A (en) * | 1996-10-02 | 1998-04-08 | Pifco Ltd | Control device for a planar electrical heating element |
| GB9710347D0 (en) * | 1997-05-21 | 1997-07-16 | Pifco Ltd | Improvements to heating apparatus |
| US6246033B1 (en) * | 1999-12-07 | 2001-06-12 | Reza H. Shah | Method and apparatus of controlling operation of range top heating elements for cooking |
| US7227083B2 (en) * | 2005-06-30 | 2007-06-05 | Ciemny William G | Thermostat and panel cover |
| US7326885B2 (en) * | 2006-05-02 | 2008-02-05 | Barnstead/Thermolyne Corporation | Hot plate with stainless steel top |
| CN102196804B (en) | 2008-10-22 | 2013-11-06 | 陶氏康宁公司 | Aminofunctional endblocked silicone polyether copolymers in personal care compositions |
| US8723085B2 (en) | 2010-11-24 | 2014-05-13 | Pioneering Technology Corp. | Temperature controlled/limiting heating element for an electric cooking appliance |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2684430A (en) * | 1950-06-05 | 1954-07-20 | Siemens Ag | Electric cooking appliance with cooking plate and thermostat |
| DE915010C (en) * | 1951-05-01 | 1954-07-12 | Gross Ag | Electric heaters |
| DE1026015B (en) * | 1952-05-16 | 1958-03-13 | Christian Buerkert | Temperature-controlled, electrically heated hotplate |
| DE1104087B (en) * | 1957-06-06 | 1961-04-06 | Karl Fischer | Electric hotplate with a temperature limiting element |
| DE1127007B (en) * | 1958-03-28 | 1962-04-05 | Karl Fischer | Electrically heated mass quick cooking plate |
| DE1123059B (en) * | 1958-12-24 | 1962-02-01 | Karl Fischer | Circuit breaker for electric hotplates |
| FR1442112A (en) * | 1965-08-04 | 1966-06-10 | Electric hob with thermal control | |
| IL29462A (en) * | 1967-02-16 | 1971-11-29 | Fischer K | Electric hot-plates |
| US3684862A (en) * | 1971-03-16 | 1972-08-15 | Mssrs E G O Elektro Gerate Bla | Thermostatically controlled electric cooker hot plate |
| US4135081A (en) * | 1974-05-10 | 1979-01-16 | Karl Fischer | Electric cooking plate with a temperature limiter |
| DE7612737U1 (en) * | 1975-04-25 | 1976-10-14 | Fischer, Karl, 7519 Oberderdingen | ELECTRIC COOKING PLATE |
| DE2620004C3 (en) * | 1976-05-06 | 1979-05-31 | Fischer, Karl, 7519 Oberderdingen | Electric hotplate with a temperature limiter |
| US4153833A (en) * | 1977-05-05 | 1979-05-08 | Karl Fischer | Electric hot plate assembly with a temperature limiter |
| DE2933296A1 (en) * | 1979-08-17 | 1981-02-26 | Karl Fischer | ELECTRIC COOKING PLATE |
| DE2943922A1 (en) * | 1979-10-31 | 1981-05-14 | Ego Elektro Blanc & Fischer | TEMPERATURE DETECTOR TO DISPLAY THE TEMPERATURE OF A GLASS-CERAMIC COOKING SURFACE |
| DE3027998A1 (en) * | 1980-07-24 | 1982-02-25 | Fischer, Karl, 7519 Oberderdingen | ELECTRIC HOTPLATE WITH OVERHEATING PROTECTOR |
| DD156060A3 (en) * | 1981-02-04 | 1982-07-28 | Horst Hase | PROTECTION DEVICE FROM OVERTEMPERATURE IN ELECTRICALLY HEATED CLOSED COOKING PLATES |
| YU44360B (en) * | 1981-08-08 | 1990-06-30 | Karl Fischer | Cooking plate with a temperature limit |
| DE3226264A1 (en) * | 1982-07-14 | 1984-01-19 | Ego Elektro Blanc & Fischer | Temperature limiter for electrical heating or warming apparatuses, especially electrical cooking plates |
-
1983
- 1983-01-20 DE DE8301364U patent/DE8301364U1/de not_active Expired
- 1983-07-01 GR GR71831A patent/GR82636B/el unknown
- 1983-07-05 EP EP83106525A patent/EP0100861B1/en not_active Expired
- 1983-07-06 US US06/511,104 patent/US4605841A/en not_active Expired - Lifetime
- 1983-07-06 PT PT76992A patent/PT76992B/en unknown
- 1983-07-06 AU AU16595/83A patent/AU560969B2/en not_active Ceased
- 1983-07-06 CA CA000431883A patent/CA1203277A/en not_active Expired
- 1983-07-06 FI FI832480A patent/FI75461C/en not_active IP Right Cessation
-
1986
- 1986-05-08 US US06/861,083 patent/US4680452A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| PT76992A (en) | 1983-08-01 |
| FI832480L (en) | 1984-01-08 |
| US4680452A (en) | 1987-07-14 |
| FI75461B (en) | 1988-02-29 |
| US4605841A (en) | 1986-08-12 |
| AU560969B2 (en) | 1987-04-30 |
| AU1659583A (en) | 1984-01-12 |
| DE8301364U1 (en) | 1987-06-25 |
| EP0100861A2 (en) | 1984-02-22 |
| FI832480A0 (en) | 1983-07-06 |
| FI75461C (en) | 1988-06-09 |
| GR82636B (en) | 1985-02-07 |
| EP0100861A3 (en) | 1984-06-06 |
| PT76992B (en) | 1986-02-03 |
| EP0100861B1 (en) | 1989-09-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1203277A (en) | Electric hotplate with a thermostat | |
| US6080968A (en) | Liquid heating vessels | |
| CA1143416A (en) | Fail safe thermostat | |
| EP2164087A2 (en) | Temperature-dependent switch | |
| CA1195364A (en) | Thermostatic switch with thermal override | |
| CA2087891A1 (en) | Device for controlling or limiting temperature in an electric cooking appliance | |
| CA1173883A (en) | Electric cooker plate with a switch for preventing overheating | |
| US2488049A (en) | Thermostatic switch | |
| CA1154068A (en) | Electric kettle with dry overload responsive and steam responsive actuating mechanisms | |
| EP1223790B1 (en) | Liquid heating vessels | |
| US4723067A (en) | Electric hotplate | |
| GB2292841A (en) | Contact arrangement for a liquid heating vessel | |
| CA1036647A (en) | Snap-action thermostat | |
| US4498069A (en) | Electric switches actuated by bimetals for one or several temperatures of response | |
| EP1072048B1 (en) | Improvements relating to thermal controls for electric heating elements | |
| WO1995019129A1 (en) | Water heating apparatus | |
| EP0385202B1 (en) | Enclosed bimetal circuit breaker | |
| US3995246A (en) | Device for controlling the temperature and protecting against excessive flow of current of electric installations | |
| US3530419A (en) | Thermostat | |
| GB2324015A (en) | Spaced bimetal actuators operating at same temperature | |
| US5337037A (en) | Device for controlling at least two luminous condition indicating signals | |
| JPS5920988A (en) | Cooking electrically heating plate with temperature protecting switch | |
| US20220336990A1 (en) | Thermostat | |
| US4374372A (en) | Modified contact strip mounting means for thermostatic switches | |
| JPS6157540B2 (en) |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |